Register new System into EntityManager. This funcion generate glue between EntityManager and System.
Systems can be registered from external dynamic library, and can be registered after adding entities too.
System mustn't be registered before components which system want to use, in this case functions call assertion.
Register new System into EntityManager. This funcion generate glue between EntityManager and System. Systems can be registered from external dynamic library, and can be registered after adding entities too. System mustn't be registered before components which system want to use, in this case functions call assertion.